The invention relates to an apparatus for flanging ventilation duct walls from sheet metal by successive edge folding and roll forming, with at least three parts mutually displaceable by hydraulic drive, of which a first part is designed as a forming roller.
An apparatus of this kind is known from DE-OS No. 1 402 838 (German laid-open Specification). This known apparatus is very complicated and expensive both in its manufacture and in servicing and maintaining it. A large part of the mechanical expense is caused by the fact that, as is quite general in the present state of the art, the substantial forces which arise in edge folding and roll forming are transmitted to a machine frame firmly anchored to the ground, so that all parts of the apparatus must be designed very heavy and large. In order to achieve the necessary rigidity, large and heavy forming rollers and beam punches must be used, since all the forces must be transmitted outwardly to the machine frame. In complicated shaping work these large forming rollers and beam punches get in the way, so that the workpieces cannot be placed in certain positions which might be otherwise desirable.
It is further necessary to have mounting and guides which are stable, large and expensive to maintain, for transmitting the large forces which arise. Finally, the machine frame or the lateral support stands must be very stable in order to absorb the forces.
In particular, however, working with the known apparatus is relatively costly, for the reason that the workpieces, which are for the most part very bulky, have to be turned after almost every pressing or bending operation. This necessitates heavy manual work. These problems become even more severe, when flanges are to be formed directly on duct walls of several meters length, since repositioning of these workpieces in the machine would be particularly expensive.
The invention aims to provide an apparatus which, by absorbing in its interior the forces which arise, permits a substantially smaller and lighter construction of said apparatus, and allows flanges with multiple folds to be formed directly onto ventilation duct walls of sheet metal in a single working step without respositioning the workpeice.
This problem is solved in accordance with the invention, by designing the second part of the apparatus as a die support containing a pressure die, and the third part as a beam punch carrier containing a beam punch which can be pressed against the pressure die, by mounting the die support and the beam punch carrier for low-friction mutual horizontal displacement, by supporting a first hydraulic drive between the die support and the beam punch carrier, by mounting the forming roller pivotably in the die support, and by supporting a second hydraulic drive between the die support and the forming roller.
The apparatus according to the invention is of substantially smaller dimensions and has simpler component parts than all known apparatuses, since all the forces which arise are absorbed immediately at their point of origin and the reaction forces thereto are applied within the apparatus at the shortest possible distance therefrom. Thus the material cost of this apparatus can be reduced to about 20%, and the finishing cost to about 30% of those costs of the known apparatuses. Machine frames and lateral support stands can be dispensed with completely. All movements of the machine parts are effected by a very simple hydraulic installation, which for preference can consist of only two pairs of cylinders. All turning, repositioning or multiple insertion of the workpiece is done away with. The workpiece is inserted once into the apparatus, and can be removed from it afterwards with the flange ready formed thereon. As a result of the very small dimensions of the apparatus even complicated, angled duct walls can be worked, since no outlying machine parts stand in the way of such workpieces. The entire apparatus consists substantially of only three simply manufactured and easily replaced component parts. Maintenance is simplified as a result; friction arising between the individual machine parts is insignificant. Lubrication is only necessary for the movement of the forming roller in the die support. The beam punch can be manufactured relatively easily by casting in steel. The pressure die can be machined (milled) into the die support. All in all, therefore, the above mentioned simple manufacture, service and maintenance is achieved.
In an advantageous embodiment the beam punch carrier is mounted for horizontal displacement on rollers which are provided in the die support; this serves to further reduce friction between the parts of the apparatus. The hydraulic drive accordingly has practically no frictional forces to overcome.
In order to arrange the roll forming, which follows after the edge folding, in a particularly simple manner, the pressure die, in a further advantageous embodiment of the invention, is partly formed from the forming roller. Thus as soon as the edge folding has finished and the beam punch has been withdrawn the forming roller can bend that part of the workpiece which abuts it into the desired final flange shape. For this there are necessary a total of only two simple maneuver of the apparatus, on the one hand a linear movement of the beam punch towards the die support and back again, and on the other hand a swivelling movement of the forming roller and its reverse. The hydraulic apparatus necessary for this purpose is quite simple, as will be appreciated.
In a prefered embodiment for forming on a duct wall, a flange of approximately triangular cross section, the die support forms two sides of the pressure die which is of substantially rectangular cross section, and the forming roller forms the third side of the pressure die. Thus that side of the pressure die which is formed by the forming roller can have an outwardly directed bevel, which agrees with a corresponding bevel on the beam punch. In this way the finished flange can receive a fixing strip parallel to the non-deformed duct walling.
In order to obtain the most stable and energy-sparing mounting of the forming roller in the die support, a further advantageous embodiment of the invention provides that the forming roller is mounted on a bearing surface of the die support by means of a sliding surface of its own, adapted to said bearing surface, for pivotal movement about the mid-axis of the bearing surface, the latter having an arcuate cross section. In this arrangement the mid-axis of the bearing surface approximately coincides, for preference, with an edge of the pressure die. It is desirable that that edge of the beam punch which cooperates with the one edge of the pressure die is bevelled.
There is thus achieved a more useful development of the workpiece sheet metal in view of the desired profile shape, for the following roll forming procedure.
Because of the large contact surface of the forming roller in the bearing surface of the die support, there is a relatively insignificant surface pressure, with consequent advantages for the working life of the apparatus.
In a preferred embodiment, the bearing surface is formed from a pipe section of bronze, the cross section of which corresponds to an arc of a circle. This pipe section is anchored in the die support, in an advantageous embodiment, by pouring a charge of casting resin into a space between the bronze pipe section and the recess of the die support. In this way there is achieved a sufficiently stable and resistant anchorage.
In order to achieve the simplest possible method of working with the apparatus according to the invention, the forming roller possesses a groove for receiving the vertically disposed duct wall before the edge folding. This groove, in the corresponding pivotal attitude of the forming roller, i.e. before the roll forming, is flush with the vertical outer surface of that section of the die support which borders on the side of the pressure die lying opposite the forming roller, said vertical outer surface being directed towards the beam punch. Thus, if a duct wall is placed vertically in this stop groove of the forming roller, and allowed to lean against the outer side of the die support, it takes up a position of 90.degree. angular displacement on the upper side of the beam punch, with the exception of the flange region which is to be formed, and is supported thereafter by the beam punch. This procedure is of particular advantage, because no special guiding elements are needed for swivelling the duct wall from the vertical position into the horizontal position. This swivelling takes place by gravity alone, on the basis of the advance of the beam punch into the pressure die and the associated traction of the end of the duct wall into the pressure die. Every movement of the duct walling in another direction than from the vertical downward into the horizontal position would demand complicated guide means. Neither is there any danger, with this movement, that the flange region would become bent with respect to the remainder of the duct walling. Nor are any special devices necessary to ensure that the duct walling lies correctly against a stop at the beginning of the working procedure, since the weight of the duct walling when inserted into the groove ensures a sufficient and correct compression force on the end edge of the duct walling in the groove.
The width of the groove is preferably greater than the thickness of the duct walling, and the side walls of the groove diverge towards the exterior, in order to ensure that bending at the flange edge of the duct walling is avoided.
Since there is particular stress on that portion of the die support which forms the pressure die, and the adjacent region, during edge folding, a further advantageous embodiment of the invention provides that the outer surface of that section of the die support which borders the side of the pressure die lying opposite the forming roller is formed of shaped blocks, which are displaceable along the die support parallel to its outer surface. Damaged or worn shaped blocks can be simply replaced by insertion of a new shaped block. Particular advantage can however be achieved by these shaped blocks, in that they can form small spaces between them, which serve for the reception of outwardly projecting folds or edges provided in the duct walling in certain circumstances. The shaped blocks in that case have simply to be arranged on the die support by displacement in such manner that a space between two adjacent shaped bodies is located wherever there is a fold or an edge, into which space the fold or edge can be inserted.
In a preferred embodiment the shaped bodies are displaceably mounted on the die support by means of a dovetail guide. Of course there are any number of other variants which permit easy sideways displacement of the shaped blocks on the die support.
The shaped bodies can form not only the outer surface of the die support facing the beam punch, but in an advantageous further development they can also form the side of the pressure die which lies opposite the forming roller. They then possess an approximately L-shaped cross section whereby the edge of the shaped body between the outer surface of the die support and the pressure die can be bevelled, thereby slowing down the swinging movement during the edge folding procedure, so that a violent 90.degree. swing of the duct wall is avoided.
Since the beam punch especially is strongly stressed in carrying out the edge folding, it is desirable that it be exchangeably secured to the beam punch carrier, so that it can be replaced when worn.
The particularly heavy loaded parts of the apparatus, especially the shaped bodies, at least the part of the forming roller that forms one side of the pressure die, and at least the front section of the beam punch desirably consist of harder material than the other parts of the apparatus, with the exception of the bearing surface between the die support and the forming roller.
The beam punch carrier, in a first embodiment, is designed as a substantially rectangular frame, which carries on a longitudinal section of its interior the beam punch which faces the die support, and whose transverse sections are mounted on the die support, preferably on the rollers mentioned.
This frame-like embodiment of the beam punch carrier can be subjected to severe bending stresses when the sheet metal is of larger dimensions or when a thicker sheet metal is being worked. In a second preferred embodiment of the invention, therefore, the beam punch carrier is designed as a substantially cubic component housed for sliding displacement in an upwardly open recess of the die support, and the beam punch carrier bears hydraulic cylinders, whose pistons project on vertical end faces of the beam punch carrier facing in opposite directions, and (whose pistons) are supported on oppositely disposed vertical end walls of the recess. In this embodiment the beam punch carrier can be designed as a substantially compact component and, with the exception of the hydraulic cylinders a massive one, so that it is more resistant to bending (stress). The vertical section of the die support is substantially C-shaped in the region of the recess.
The hydraulic cylinders can be used as inserted parts in holes bored in the beam punch carrier or (advantageously) can be worked directly into the beam punch carrier.
A substantially larger force is necessary for carrying out the edge folding than for withdrawing the beam punch from the pressure mould. In a useful embodiment of the invention, therefore, a larger number of adjacent parallel hydraulic cylinders is provided for producing the folding motion of the beam punch carrier than for producing the return movement. For example, twelve strong hydraulic cylinders can be provided, arranged mutually adjacent in a row, to produce the folding movement, while three smaller hydraulic cylinders suffice for producing the return movement. By means of the multiplicity of hydraulic cylinders, the pressure force during the folding process is uniformly distributed over the length of the beam punch. Therefore hardly arises any bending stress.